Photographic products and processes



July 11, 1961 H. c. HAAs 2,992,104

PHOTOGRAPHIC PRODUCTS AND PROCESSES Filed March 3, 1958 I2 ,\{Nrl'ro Carboxymelhyl Cellulose Loyer Conl'cxinng o Color Providing Subslunce I4 Fholosensl've Loyer FIG. l

Suppori' 2O {Loyer of Nlro Carboxymel'hyl Cellulose 2l Conl'cxnng Cycxn Dye Developer 2 Red Sensl've Emulsion 23 Spacer Loyer 24 C {Loyer' of Nil'ro Carboxymel'hyl Cellulose 25 Conlclnlng Mogenl'a Dye Developer Green Sens'l've Emulsion 26 Spacer Loyer 27 /f/ Loyer of Nilro Carboxymel'hyl Cellulose 28 Conluinng Yellow Dye Developer Blue Sensil'ive Emulsion FIG. 2

MGM

INVENTOR.

lATOgNEYS United States Patent O 2 992 104 PHOTOGRAPHIC PRDCTS AND PROCESSES Howard C. Haas, Arlington, Mass., assignor to Polaroid Corporation, Cambridge, Mass., a corporation of Dela- Ware Filed Mar. 3, 1958, Ser. No. 718,783 21 Claims. (Cl. 96-29) The present invention is concerned with photography and more particularly with novel photographic products and novel photographic processes utilizing said products.

One object of the present invention is to provide novel photosensitive elements for color dilusion transfer processes comprising at least one layer of a nitro carboxymethyl cellulose polymer.

Another object of the present invention is to provide improved color diffusion transfer processes utilizing said photosensitive element.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the several steps and the relation and order of one or more of such steps with respect to each of the others, and the product possessing the features, properties and the relation of elements which are exemplied in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawing wherein:

FIGURE 1 is a diagrammatic cross-sectional view of one embodiment of a photosensitive element of this invention; and

FIG. 2 is a diagrammatic cross-sectional view of one embodiment of a multilayer photosensitive element within the scope of this invention.

The present invention is particularly related to color diffusion transfer processes. In such processes a photosensitive element including a silver halide emulsion layer is exposed to create therein a latent image. The latent image is developed and, concurrent with and under the control of this development, a positive imagewise distribution of mobile color-providing materials is formed. At least a portion of these color-providing materials is transferred by means of an alkaline aqueous processing liquid to a superposed image-receiving llayer to form a colored positive image thereon. As examples of such processes, mention may be made of the processes disclosed and claimed in the copending U.S. application of Howard G. Rogers, Serial No. 748,421, filed July 14, 1958 (now Patent No. 2,983,606, issued May 9, 1961), which is a continuation-in-part of his now abandoned application Serial No. 415,073, filed March 9, 1954, wherein dye developers (i.e., compounds which contain in the same molecule both the chromophoric system of a dye and also a silver halide developing function) are the color-providing materials, the processes claimed and disclosed in U.S. Patent No. 2,647,- 049, issued July 28, 1953, to Edwin H. Land, wherein color developers are employed to develop the latent image and color couplers are the color-providing materials, and the processes disclosed in U.S. Patent No. 2,774,668,

issued December 18, 1956, to Howard G. Rogers, wherepermeable layer in the photosensitive element. The separate alkali-permeable layer may be placed either in front of or behind the photosensitive emulsion with which it is associated; however, in a preferred embodiment it is placed behind, i.e., on the side of the emulsion which is most distant from the photographed subject when the emulsion is exposed, and preferably also adapted to be most distant from the image-receiving element when in superposed relationship therewith. In carrying out the processes, the photosensitive element is exposed and wetted with an aqueous alkaline processing solution, for example, by immersing, coating, spraying, flowing, etc., in the dark, and the photosensitive element is superposed prior to, during or after wetting on an image-receiving element. In a preferred embodiment the aqueous alkaline processing solution contains a viscosity-increasing compound and is applied to the photosensitive element in a substantially uniform layer as the photosensitive element is brought into superposed position with the image-receiving element. The alkaline aqueous processing solution permeates the photosensitive emulsion and alkali-permeable layers and solubilizes the color-providing materials to provide a substantially uniform distribution of the color-providing materials therein. As the processes proceed, the exposed silver halide image is developed and the color-providing materials in the exposed areas are immobilized or precipitated, thereby providing an imagewise distribution of mobile color-providing materials in the unexposed areas. At least a portion of the color-providing materials in the unexposed areas is transferred to and imbibed on the image-receiving element to form the positive image. The positive image is viewed by stripping the image-receiving element from the photosensitive element.

When the color-providing materials are incorporated into a separate alkali-permeable layer, it is desirable that said alkali-permeable layer have good dry and wet adhesion to the other layers present, to avoid delamination during coating and rewinding operations or during processing, wherein portions of the photosensitive element .would adhere to the surface of the image-receiving element. It is further desirable that the alkali-permeable layer readily release the color-providing materials in order to make available the maximum amount of said materials for forming the positive image. In the past, the use of film-forming polymers, such as cellulose acetate hydrogen phthalate, as the material for the alkali-permeable layer, has been proposed.

It has been discovered that the use of nitro carboxymethyl cellulose (free acid) as the alkali-permeable and alkali-swellable material provides superior adhesion and at least as good if not better releasability of the colorproviding materials as that obtained using cellulose acetate hydrogen phthalate. The releasability of the colorproviding materials is especially marked and demonstrable when dye developers are the color-providing materials.

Dye developers, .as noted above, are compounds which contain in the same molecule both the chromophoric system of a dye and also a silver halide developing function. By a silver halide developing function is meant a radical which is capable of developing an exposed silver halide image, and more particularly, benzenoid developing groups. A preferred silver halide developing radical in such compounds is a hydroquinonyl group. Examples of representative dye developers are given in the previously mentioned U.S. application of Howard G. Rogers, Serial No. 748,421. Additional useful dye developers are described in the following copending U.S. applications:

Application Serial No. 449,514, filed August l2, 1954, in the names of Elkan R. Blout and Myron S. Simon, now abandoned and replaced by continuation-in-part application Serial No. 849,727, led October 30, 1959.

Application Serial No. 450,208, filed August 16, 1954, in the names of Elkan R. Blout, Saul G. Cohen, Milton Green and Myron S. Simon, now abandoned land replaced by continuation-impart application Serial No. 5,- 804, filed October 18, 1958.

Application Serial No. 471,542, tiled November 26, 1954, in the names of Elkan R. Blout, Saul G. Cohen, Milton Green, Howard G. Rogers, Myron S. Simon and Robert B. Woodward, now abandoned and replaced by continuation-impart application Serial No. 1,442, led January 11, 1960.

Application Serial No. 478,922, tiled December 30, 1954, in the names of Elkan R. Blout, Marilyn R. Cohler, Milton Green, Myron S. Simon and Robert B. Woodward, now abandoned and replaced by continuation-in-part application Serial No. 824,785, led July 3, 1959.

Application Serial No. 612,045, tiled September 25, 17956, in the names of Elkan R. Blout, Milton Green and Howard G. Rogers.

Application Serial No. 612,052, filed September 25, 1956, in the names of Milton Green and Howard G. Rogers.

Application Serial No. 612,053, tiled September 25, 1956, in the name of Myron S. Simon.

Application Serial No. 612,054, led September 25, 1956, in the names of Helen P. Husek and Myron S. Simon.

Application Serial No. 612,055, led September 25, 1956, in the name of Helen P. Husek.

In color dilfusion transfer processes employing dye developers, the dye developer, as mentioned previously for color-providing substances in general, is preferably placed in a separate alkali-permeable layer behind the photosensitive layer. Upon processing, the alkaline aqueous processing solution permeates to the separate alkali-permeable layer and solubilizes the dye developer therefrom. As the process proceeds, the latent silver halide image in the photosensitive element is developed and, as a result of this development, the dye developer in the exposed areas is oxidized and substantially immobilized. At least a portion of the unreacted dye developer is imbibed on a superposed image-receiving element to create thereon the positive dye image. In such processes the immobilization of the dye developers in the exposed areas is apparently due, at least in part, to a change in the solubility characteristics of the dye developer upon oxidation. It may also be due in part to a tanning effect on the emulsion by the oxidized developer.

FIG. 1 of the accompanying drawing illustrates one embediment of a photosensitive element for use in color diiusion transfer processes wherein nitro carboxymethyl cellulose is used as the material for a separate alkalipermeable layer. The photosensitive element shown therein comprises a support 10, a layer 12 of nitro carboxymethyl cellulose containing a color-providing substance and a photosensitive layer 14.

In preparing photosensitive elements of the type mentioned above and in preparing other photosensitive elements within the scope of this invention, the nitro carboxymethyl cellulose layers may be conveniently applied from coating solutions containing said nitro carboxymethyl cellulose. The preferred coating solutions comprise 2 to 10% of polymer; however, this amount may be varied to suit particular needs. The coating and drying operations may be carried out according to procedures well known to the art. The color-providing substances which are to be disposed in the separate alkalipermeable layer may be incorporated into the coating solution and applied therewith, or they may be imbibed onto the layer after its application. When the colorproviding substances are incorporated into the coating solutions, they may be dispersed or solubilized therein, depending upon the color-providing substance itself, the solvent used and the state desired for the diffusion transfer processes. As examples of suitable solvents for nitro carboxymethyl cellulose which can be used in preparing the coating solutions, mention may be made of tetrahydrofuran and acetone. When the coating solution is applied directly to a support such, for example, as baryta, cellulose acetate, etc., said support may be first subcoated with 4 a suitable material such as gelatin to further enhance the adhesion.

Nitro carboxymethyl cellulose is also suitable as an alkali-permeable material in integral multilayer photosensitive elements for use in multicolor diffusion transfer processes. As an example of such photosensitive elements, mention may be made of the photosensitive elements disclosed and claimed in the copending U.S. application of Edwin H. Land and Howard G. Rogers, Serial No. 565,135, led February 13, 1956, wherein at least two selectively sensitized photosensitive strata are superposed on a single support and are processed, simultaneously and without separation, with a single common image-receiving element. A suitable arrangement of this type comprises a support carrying a red-sensitive silver halide emulsion stratum, a green-sensitive silver halide emulsion stratum, and a blue-sensitive silver halide emulsion stratum, said emulsions having associated therewith, respectively, a cyan dye developer, a magenta dye developer and a yellow dye developer. In one of the preferred embodiments of photosensitive elements of this type, the dye developers are disposed in separate alkali-permeable layers behind thephotosensitive silver halide emulsion stratum with which they are associated. As in monochromatic photosensitive elements, superior adhesion and, as good if not better, releasability of the color-providing materials are obtained with nitro carboxymethyl cellulose than are obtained with cellulose acetate hydrogen phthalate.

A multilayer photosensitive element of the type just mentioned is illustrated in FIG. 2 of the accompanying drawing. A support 20 carries a layer 21 of nitro carboxymethyl cellulose containing a cyan dye developer; a layer 2.2 of a red-sensitive silver halide emulsion; a spacer layer 23, e.g., of gelatin or polyvinyl alcohol; a layer 24 of nitro carboxymethyl cellulose containing a magenta dye developer; a layer 25 of a green-sensitive silver halide emulsion; a spacer layer 26; a layer 27 of nitro carboxymethyl cellulose containing a yellow dye developer; and an outermost layer 28 of a blue-sensitive silver halide emulsion. In certain instances, for example when the yellow dye developer is not present in a state capable of functioning as a filter, a yellow dye lter is placed in spacer layer 26.

Both the monochromatic and multicolor photosensitive elements within the scope of this invention may be used in roll lm units which contain a plurality of photosensitive frames'. are especially useful in composite lm units intended for use in a Polaroid Land Camera, sold by Polaroid Corporation, Cambridge 39, Mass., or similar camera structure such, for example, as the camera forming the subject matter of U.S. Patent No. 2,435,717. In general, such lm units comprise a photosensitive roll, a roll of imagereceiving material and a plurality of pods containing an aqueous alkaline processing solution. The rolls and pods are so associated with each other that, upon processing, the photosensitive element may be superposed on the image-receiving element and the pods may be ruptured to spread the aqueous alkaline processing solution between the superposed elements. The nature and construction of the pods used in such units are well known to the art. See,`for example, U.S. Patent Nos. 2,543,181 and 2,634,- 886, issued to Edwin H. Land.

In the photosensitive elements of :this invention, in general, and especially when they are used in roll lrn. units such as described above, it is desirable that the alkalipermeable materials provide good dry adhesion as well as wet adhesion in order to withstand the stresses and strains to which such elements are commonly subjected. It has been found that the nitro carboxymethyl cellulose polymers of this invention, containing a given amount of a `color-providing material, provide better dry adhesion than cellulose acetate hydrogen phthalate polymers containlng anequivalent amount of the color-providing materi The photosensitive elements of this invention- .ticular needs.

Nitro carboxymethyl cellulose polymers suitable for use in preparing the novel photosensitive elements of this invention may be prepared by nitrating a carboxymethyl cellulose polymer with a suitable nitrating agent such, for exmple, as a mixture of phosphorous pentoxide and 90% -fuming nitric acid. The alkali permeability of the resulting polymers, in general, will vary with the degree of nitration and the ratio of carboxyl to nitro groups. Generally, the permeability will increase with the number of carboxyl groups present and decrease with an increasing degree of nitration. The preferred nitro carboxymethyl cellulose polymers for use in the processes of this invention contain at least about 0.7 carboxyl group per anhydrous glucose unit and have a ratio of carboxyl groups to nitro groups of about 0.7 to 1.8; however, the number of carboxyl groups present and the ratio of carboxyl to nitro groups present may be varied to suit par- Carboxymethyl cellulose polymers containing varying amounts of carboxyl groups from which nitro carboxymethyl cellulose polymers of dilferent alkali permeabilities can be prepared, are readily available commercially. As examples of such polymers, mention may be made of Hercules high viscosity, C.M.C., type 70 and type 120 sold by Hercules Powder Co., Wilmington, Delaware.

The following nonlimiting examples illustrate the preparation of nitro carboxymethyl cellulose polymers suitable for use in the photosensitive elements of this invention.

Example 1 A nitrating mixture was made up by mixing 404 gms.

of phosphorous pentoxide in 1000 gms. of 90% nitric acid. 30 gms. of Hercules high Viscosity type 70 sodium carboxymethyl cellulose (comprising about 0.7 carboxymethyl group per glucose segment) were added to 500 gms. of the nitrating mixture, and the resulting combination was stirred for 21/2 hours at room temperature. The polymer was then precipitated by the addition of water; filtered and washed with water. The polymer was further puried by dissolving in acetone, reprecipitating with water, filtering and rewashing with Water. An analysis of a dried sample showed 8.8% nitrogen.

Example 2 30 gms. of Hercules high viscosity type 120 sodium carboxymethyl cellulose (comprising about 1.2 carboxymethyl groups per glucose segment) were added to 500 gms. of nitrating solution, as prepared in Example l, and the two were stirred for 21/2 hours at room temperature. Water was added to bring about precipitation, and the resulting polymer was iil-tered and washed with water. The polymer was dissolved in acetone, precipitated with water and dried.

The following nonlimiting examples illustrate the preparation and use of the novel photosensitive elements of this invention.

Example 3 Percent Sodium carboxymethyl cellulose 5.0 Sodium hydroxide 3.0 1-phenyl-3-pyrazolidone 0.8

between said photosensitive element and an image-receiving element as said elements were brought into superposed relationship. The image-receiving element comprised a cellulose acetate-coated baryta paper which had been coated with an ethanol solution containing 4% Nylon Type F8 (trade name of E. I. du Pont de Nemours & Co., Wilmington, Delaware, for N-methoxymethyl polyhexamethylene adipamide). After an imbibition period of approximately one minute, the image-receiving element was separated and contained a dense yellow positive dye image of the photographed subject. No signs of delamination in the photosensitive element were observed.

Example 4 A photosensitive element was prepared as in Example 3 except that 3% of 1-phenyl-3-N-n-hexyl-carboxamido- 4- [p- 2',5 '-dihydroxyphenethyl) -phenylazo] -5 -pyrazolone and 2% of nitro carboxymethyl cellulose (prepared as in Example 2) were used in the tetrahydrofuran coating solution. Upon processing the photosensitive element, as in Example 3, a yellow positive transfer image was obtained. The nitro carboxymethyl cellulose layer released the dye well and no signs of delamination were observed.

Superior dry adhesion was also observed in tests of the negatives prepared in Examples 3 and 4 as compared with similar negatives employing cellulose acetate hydrogen phthalate.

Nitro carboxymethyl cellulose is further suitable for use in screen type photosensitive elements such las disclosed in the aforementioned U.S. application of Howard G. Rogers, Serial No. 748,421, and also the copending U.S. application of Edwin H. Land, Serial No. 448,441, iiled August 9, 1954 (now U.S. Patent No. 2,968,554, issued January 17, 1961), wherein at least two selectively Isensitized silver halide emulsions are arranged in the form of a screen and the color-providing substances, as in multilayer photosensitive elements, are preferably placed in a sepa-rate alkali-permeable layer in back of the photosensitive emulsion with which they are associated.

It should be noted that nitro carboxymethyl cellulose, because of its superior adhesive properties, is useful as a subbing agent for photographic products in general; for example, it may be used to bind a silver halide gelatin emulsion to a suitable support such, for example, as cellulose acetate, baryta, etc.

It should be further noted that nitro carboxymethyl cellulose polymers are useful as spacer layers in multilayer photosensitive elements such, for example, as layer 26 in the photosensitive element illustrated in FIG. 2, particularly where the dyes are incorporated in other materials to form, e.g., layer 27.

Since certain changes may be made in the above product and process without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

VWhat is claimed is:

1. A photosensitive element comprising a support bearing in turn on one surface a layer of nitro carboxymethyl cellulose polymer having a color-providing substance disposed therein and, contiguous with said layer, a photosensitive gelatino silver halide emulsion layer, said color-providing substance being selected from the group consisting of color couplers and dyes.

2. A photosensitive element as defined in claim l wherein said nitro carboxymethyl cellulose polymer contains at least about 0.7 carboxyl group per anhydrous glucose unit.

`3. A photosensitive element as defined in claim 1 wherein the ratio of carboxymethyl radicals to nitro radicals in said nitro carboxymethyl cellulose polymer is about 0.7 to 1.8.

4. A photosensitive element comprising a photosensitive gelatino silver halide emulsion layer and, contiguous with said layer, 'a .layer `of nitro carboxymethyl cellulose polymer, said Vnitro carboxymethyl cellulose polymer layer having disposed therein a dye developer, said dye developer 'being a compound which is both a dye and a silver'halide developing agent.

5. A photosensitive element as dened in claim 4 wherein said nitro carboxymethyl cellulose polymer contains at 'least about 0.7 carboxyl group per anhydrous glucose unit.

6. A photosensitive element as dened in claim 4 wherein the ratio of carboxymethyl radicals to nitro radicals in said nitro carboxymethyl cellulose polymer is about `0.7 to 1.8.

7. In a photosensitive element comprising a plurality of photosensitive gelatino silver halide emulsions, each of said emulsions being selectively sensitized to difierent portions of the spectrum, and a dye developer associated with each of said emulsions, said dye developer being a compound which is both a dye and a silver halide developing agent, at least one of said dye developers disposed in a layer Vof nitro carboxymethyl cellulose polymer, said layer of nitro carboxymethylcellulose polymer being behind and contiguous to the emulsion it is associated with.

8. A photosensitive element as delined in claim 7 wherein said nitro carboxymethyl cellulose polymer contains at least 0.7 carboxyl group per anhydrous glucose unit.

9. A photosensitive element as delined in claim 7 wherein the ratio of carboxymethyl radicals to nitro radicals in said vnitro carboxymethyl cellulose polymer is about 0.7 to 1.8.

10. In a process of forming a photographic image in color wherein a latent image contained in an exposed gelatino silver halide emulsion layer of a photosensitive element is developed to provide an imagewise distribution of color-providing substances in said emulsion, said color-providing substances being selected from the group consisting of color couplers and dyes, and said imagewise distribution of color-providing substances is transferred by an alkaline aqueous processing solution to a superposed image-receiving element to impart to said image-receiving element a positive colored image, the improvement of disposing the color-providing substance in a layer of nitro carboxymethyl cellulosepolymer, said ylayer of nitro carboxymethyl cellulose polymer being behind and contiguous to the silver halide emulsion layer and, Yduring processing, permeating said photosensitive .element with an aqueous alkaline processing solu- 13. A process of. forming transfer images in color which comprises exposing a photosensitive element containing a gelatino silver halide emulsion layer and a layer of nitro carboxymethyl cellulose'polymer containing a dye developer, said dye developer beinga compound which is both a dye and a silver halide developing agent, said layer of nitro carboxymethyl cellulose polymer being contiguous to said silver halide emulsion layer; permeating said photosensitive emulsion with an aqueous alkaline processing solution; solubilizing at least a portion of said dye developer from said nitrocarboxmethyl cellulose layer; developing the latent image in the exposed emulsion in the presence of said dye developer, whereby said dye developer is immobilized in eX- posed areas but remains mobile in unexposed areas of said emulsion, thereby providing an imagevvise distribution of mobile dye developer; and transferring at least a p0rtion of said mobile dye developer to a superposed imagereceiving element.

14. A process as defined in claim 13 wherein said nitro carboxymethyl cellulose polymer contains at least about 0.7 carboxyl group per anhydrous glucose unit.

l5. A process as defined in claim 13 wherein the ratio of carboxymethyl radicals to nitro radicals in said nitro carboxymethyl cellulose polymer is about 0.7 to 1.8.

16. A process as dened in claim 13 wherein said layer of nitro carboxymethyl cellulose is behind the silver halide emulsion layer.

17. A photographic element comprising a support, having on at least one surface a subbing layer of nitro carboxymethyl cellulose and a gelatino silver halide emulsion layer adjacent to said subbing layer.

18. A photographic element as defined in claim 17 wherein the ratio of carboxymethyl radicals to nitro radicals in said nitro carboxymethyl cellulose is about 0.7 to 1.8.

19. A photographic element as defined in claim l7 wherein said nitro carboxymethyl cellulose polymer contains at least about 0.7 carboxy group per anhydrous glucose unit.

.20. A photosensitive element comprising a support bearing a layer of nitro carboxymethyl cellulose polymer having a color coupler disposed therein, and a photosensitive gelatino silver halide emulsion layer, said silver halide emulsion layer being contiguous with said layer of nitro carboxymethyl cellulose.

2l. A photosensitive element comprising a support bearing a layer of nitro carboxymethyl cellulose having a dye Ydisposed therein, and a photosensitive gelatino silver halide emulsion layer, said silver halide emulsion layer being contiguous with said layer of nitro carboxymethyl cellulose.

References Cited in the ile of this patent UNITED STATES PATENTS 

10. IN A PROCESS OF FORMING A PHOTOGRAPHIC IMAGE IN COLOR WHEREIN A LATENT IMAGE CONTAINED IN AN EXPOSED GELATINO SILVER HALIDE EMULSION LAYER OF A PHOTOSENSITIVE ELEMENT IS DEVELOPED TO PROVIDE AN IMAGEWISE DISTRIBUCOLOR-PROVIDING SUBSTANCES BEING SELECTED FROM THE GROUP CONSISTING OF COLOR COUPLERS AND DYES, AND SAID IMAGEWISE DISTRIBUTION OF COLOR-PROVIDING SUBSTANCES IS TRANSFERRED BY AN ALKALINE AQUEOUS PROCESSING SOLUTION TO A SUPERPOSED IMAGE-RECEIVING ELEMENT TO IMPART TO SAID IMAGE-RECEIVING ELEMENT A POSITIVE COLORED IMAGE, THE IMPROVEMENT OF DISPOSING THE COLOR-PROVIDING SUBSTANCE IN A LAYER OF NITRO CARBOXXYMETHYL CELLULOSE POLYMER, SAID LAYER OF NITRO CARBOXYMETHYL CELLULOSE POLYMER BEING BEHIND AND CONTIGUOUS TO THE SILVER HALIDE EMULSION LAYER AND, DURING PROCESSING, PERMEATING SAID PHOTOSENSITIVE ELEMENT WITH AN AQUEOUS ALKALINE PROCESSING SOLUTION AND SOLUBILIZING SAID COLOR-PROVIDING SUBSTANCE FROM SAID NITRO CARBOXYMETHYL CELLULOSE LAYER. 